# Window Light & Day\-Night Cycle

By Luke Sheldon

Topic: Earth & Geography

[Open the interactive Jig](https://ask.jig.com/j/Eouv9NHMAcQg)

## Guide

### 1. Sunlight through a window

Morning sun pours through a window into a quiet room\. Follow one whole day, from sunrise to a starry night, and find out why the light keeps changing\. Drag the room to turn it\.

### 2. The Sun crosses the sky

Earth spins once a day, so the Sun seems to move across the sky by 15 degrees every hour\. Slide the time and watch the bright patch of sunlight creep across the floor\.

This window faces south\. In the northern half of the world, sunshine comes in all day\.

### 3. Why you can see the beams

From the side, light itself is invisible\. You see beams because tiny specks of dust in the air bounce some light toward your eyes\. The window bars split the light into separate shafts\.

Clean air hides the beams\. More dust makes them stronger\.

### 4. Long golden light

Late in the day the Sun sinks low, so its light enters almost sideways\. The bright patch stretches across the room and climbs the wall\. It turns golden because it crosses far more air, which scatters the blue away\.

### 5. Open the window

Grab the lower window, called the sash, and slide it up\. A breeze drifts in and swirls the dust, and the garden sounds louder\. Where the sash moved, light no longer crosses its wooden bars\.

### 6. Twilight, then night

After sunset the sky glows deep blue for over an hour, then stars come out\. Moonlight is sunlight bounced off the Moon, hundreds of thousands of times dimmer than sunshine, so it makes no beams\.

Direct sunshine can reach 100,000 lux\. A full Moon gives under 1 lux\.

### 7. Switch on the lamp

Tap the lamp to switch it on\. Energy flows from the wall socket along the cord, and the bulb fills the room with warm light\. Now the room is brighter than outside, so the glass shows a reflection of the room\.

Each glass surface reflects about 4 percent of the light that hits it\.

### 8. A whole day

Play a full day in 24 seconds: sunrise, bright noon, golden evening, twilight and night\. Watch the thermometer as well\. Sunshine warming the floor makes the room a few degrees warmer by afternoon\.